1. Field of the Invention
This invention relates in general to electrical terminals and more particularly to high current terminals that are engaged and then rotated relative to each other to interlock and complete an electrical connection.
2. Discussion of Related Art
A power distribution center or module (PDM) is commonly used in automotive vehicles to simplify and organize electrical system wiring. The PDM consolidates relays, fuses, branch circuits, connectors and other electrical components in a single location and eliminates multi-branch wiring. The typical PDM incorporates a bus bar or similar conductor into a housing. The housing often includes a surface having a plurality of receptacles for receiving the electrical connectors, fuses, relays and other circuit components. A PDM cover usually fits over the surface and insulates and protects the components. The bus bar is routed beneath the surface and has a plurality of blade-like projections that protrude into some or all of the receptacles to make electrical contact with the components when they are mounted on the surface. The bus bar supplies electrical power to the components for meeting the vehicle electrical circuit requirements. The electrical power is usually provided to the bus bar through a high current cable from the vehicle alternator and/or battery.
Often, in high power connections, an eyelet terminal is crimped or soldered on the end of the high current cable. The eyelet terminal fits over a threaded stud extending through the bus bar in the PDM, and a nut is used to tighten the eyelet terminal into electrical connection with the bus bar. Sometimes a separate bolt and nut are used to secure the terminal to the bus bar. In either system, a retention feature of this type requires tools, often with torque monitoring capabilities, to fasten the terminal to the bus bar. The use of tools provides opportunities for cross-threading or improperly torqued attachments that could cause loose connections. Inadequately tightened connections in turn could lead to overheating, electrical arcing, loss of contact and other undesirable events.
Co-pending, commonly owned U.S. patent application Ser. No. 11/204,033, filed Aug. 16, 2005, attempts to address some of these problems by using a manually operated lever to rotate a cam surface against a harness terminal. This forces the terminal against a bus bar extending from the PDM. The design of the cam surface along with a latch for the lever act to hold the terminal against the bus bar.
Other known designs require two individual terminals, one attached to the harness and the other separately attached to the bus bar, with an additional connector to maintain the interface between the two terminals. Some lower current grounding connections use terminals that can be locked together by engaging the terminals and twisting one terminal relative to the other, but still require fasteners to complete the connection. U.S. Pat. No. 5,759,056, for example, discloses identical eyelet terminals that have circumferentially spaced tabs formed on an inner edge of the eyelet. When one terminal is placed on top of the other and rotated, the tabs hook together and interlock the terminals in planar contact. A bolt is then passed through each eyelet to fasten the terminals to a grounding point.